There are a number of medical devices that can have portions implanted into a patient's vasculature. For example, devices such as pacemakers, defibrillators, and implanted cardioverter defibrillators (“ICDs”) have been successfully implanted for years for treatment of heart rhythm conditions. Pacemakers are implanted to detect periods of bradycardia and deliver electrical stimuli to increase the heartbeat to an appropriate rate, while ICDs are implanted in patients to cardiovert or defibrillate the heart by delivering electrical current directly to the heart. Another implantable defibrillation device can detect an atrial fibrillation (AF) episode and deliver an electrical shock to the atria to restore electrical coordination.
Next generation defibrillators, ICDs, pacemakers, etc., may take the form of elongated intravascular devices, such as those described, for example, in U.S. patent application Ser. No. 10/454,223, entitled “IMPLANTABLE INTRAVASCULAR DEVICE FOR DEFIBRILLATION AND/OR PACING,” filed Jun. 4, 2003; U.S. patent application Ser. No. 10/453,971, entitled “DEVICE & METHOD FOR RETAINING A MEDICAL DEVICE WITHIN A VESSEL”, filed Jun. 4, 2003; as well as U.S. patent application Ser. No. 10/862,113, entitled “INTRAVASCULAR ELECTROPHYSIOLOGICAL SYSTEM AND METHODS,” filed Jun. 4, 2004, each of which is hereby incorporated herein by reference. These devices often contain electric circuitry and/or electronic components that must be hermetically sealed to prevent damage to the electronic components and the release of contaminants into the bloodstream. This can require the use of expensive shielding and insulating components, which have to be designed in a way to prevent problems with clotting and obstruction of blood flow. Further, due to the length of these implantable devices, which in some cases can be approximately 10-60 cm in length, the devices must be flexible enough to move through the vasculature while being sufficiently rigid to protect the internal components. It is desirable to simplify these devices to allow for the use of standard components that can lower the cost and complexity of these devices while still providing the necessary flexibility and support.